1. Field of the Invention
The invention relates to the field of radar cross-section testing of models and, in particular, to support apparatus for the models.
2. Description of Related Art
The typical method of supporting a radar cross-section (RCS) test article, such as a model of an aircraft on a radar test range, is to mount it on a support pylon. The design of radar test ranges is discussed in U.S. Pat. No. 4,947,175, "Radar Range " by D. D. Overholser. If the model is very small and light in weight, the pylon can be made of low dielectric foam material. Such foam pylons are disclosed in U.S. Pat. Application Ser. No. 07/562,877, "Support Pylon For Radar Cross-Section Model Testing " by C. J. Larson (common assignee). If the model is large, the pylon is usually made of metal or high strength composite material having a low RCS shape. Additionally, the pylon is coated with radar absorbing materials. A rotator mechanism is mounted on top of the pylon and is coupled to the model so that it can be rotated about both the pitch and yaw axis. However, the size of the pylon and rotator increases proportionally with the size of the model and for certain radar frequencies, the pylon significantly interferes with the test results.
This has led to the use of cable suspension systems for the support of the models. In detail, such systems usually consist of a series of support columns with the model suspended by a set of upper cables there between. Additionally, the model is attached by a set of lower cables to a ground mounted rotator located vertically below it. By crossing two or more of these lower support cables, rotational force is applied to the model when the rotator is activated (rotated). However, when attempts are made to rotate a model already set at a specific pitch angle, the pitch angle will change as the azimuth changes. This requires that the length of these "vertical " support wires be adjusted as the model is rotated. Difficulty is encountered when attempting to continuously change the length of individual cables as the model is rotated. Also, such cable adjusting systems are expensive.
Therefore, it is a primary object of the invention to provide a RCS model support system for testing the model at a radar test range.
It is another primary object of the subject invention to provide a RCS model suspension type support system for testing the model at a radar test range.
It is a further object of the subject invention to provide a RCS model suspension type support system for testing the model at a radar test range, with the support system having an inexpensive system for maintaining proper pitch angle of the model as the model is rotated in the azimuth plane.
It is a further object of the subject invention to provide a RCS model suspension type support system for testing the model at a radar test range, with the support system having a simple and accurate system for maintaining the proper pitch angle of the model as the model is rotated in the azimuth plane.